Add deterministic protocol replay harness

src/main.zig

@@ -1,5 +1,6 @@
 const std = @import("std");
 const protocol = @import("protocol.zig");
+const replay = @import("replay.zig");
 const session = @import("session.zig");
 const socket = @import("socket.zig");
 
@@ -115,6 +116,7 @@ fn collectRemainingArgs(allocator: std.mem.Allocator, args: *std.process.Args.It
 
 test {
     _ = protocol;
+    _ = replay;
     _ = session;
     _ = socket;
 }